2. Intraoperative: Subjects will all undergo induction of anesthesia by inhalation of sevoflurane and oxygen. An intravenous catheter (IV) will be placed, followed by lidocaine 2mg/kg IV. The airway device will be placed (LMA or ETT). As required for the procedure, the subject will be placed in a left lateral decubitus (left side down) position. Maintenance of anesthesia will be provided with sevoflurane at a concentration of 1.5-2 MAC, or higher if deemed appropriate for the clinical setting as judged by the anesthesiologist. All participants will be given the anti-nausea medicine ondansetron 0.1mg/kg (maximum 4 mg) after placement of the airway device. When the endoscope is removed at the completion of the procedure, the patient will be returned to the supine position. The sevoflurane will be discontinued and the airway device will be removed when the anesthesiologist deems it appropriate. Prior to leaving the OR, the anesthesiologist may give pain or anti-anxiety medicine as needed.